Canon’s new 600mm and 800mm lenses

Started 3 months ago | Discussions thread
AiryDiscus Senior Member • Posts: 2,140
Re: DoF of Canon’s new 600mm and 800mm lenses

bclaff wrote:

Jack Hogan wrote:

alanr0 wrote:

... my guess is that this is due to a small focusing error, possibly combined with a change in spherical aberration in the preceding optics. ...

Bill, slightly OT. You know I am a raytracing noob and the first time I tried it recently I was flabbergasted at the amount of spherical aberration from a single lens with perfectly spherical surfaces.

Yes, a simple single element will have significant spherical aberration.

That depends on the conjugates and shape.  For an object at infinity and n ~= 1.5, placing the surface with larger curvature towards the object and giving the other a radius ~6x larger is called "best form."  You can find these for low cost from any optics supplier.  The less curved surface is "almost" planar.  as n increases, the second surface becomes more planar.

Biconvex is optimum for a unit relay.

Welford's Aberrations of Optical Systems is terse, pragmatic, and rigorous for raytracing, in the sense that you could learn how to write a good raytracer by reading it.

Smith's MOE could teach you what it means.

The original author of LightTools has released an open source raytracer.  Odds are quite high there isn't a better open source one out there, since he is probably among the most knowledgeable people out there on the topic.

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